N-fs-phenylethyl



United tate mfl TQ ethyl)-4-phenyl 4-carbomethoxypiperidine and N-(B- phenylethyl)-4-phenyl-4-carboethoxy-piperidine, and salts thereof, have been found to be only one-third as toxic OXYPIPERIDINES AND PROCESSES F PREPAR- as meperidine and to be twice as potent as analgesics; at ING THEM 5 comparable analygesic activity, the toxicity of ;N-(/3- Karl Pfister Westfield, and Arsenio A. Pessolano, phenyletliyl)-4-phenyl-4-carbomethoxypiperidine and N- Linden, NJ assignors to Merck & Co'., Inc., Rahway, '(,B-phenylethyl)-4-phenyl-4-carboethoxy-piperidine is only 3 col'pol'afioll 9 New-Jersey one-sixth that of meperidine. I N0 Drawing. Filed May 26, 1955, Ser. No. 511,413 The N- (fl-phenylethyl)-4-phenyl-4carbomethoxypiperi- 5 Claims. ((31.260-29-43) dine, (fi-p y e y -P y yp pe dine, and salts thereof, can be prepared by reactions which may be chemically represented as follows:

v 2,947,753 N-(B-PHENYLETHYL) -4- PHENYL 4 CARBOALK- This invention is concerned generally with novel C uHs C 0 O R p i OoHi @cmonnH =';-H|O0|*CHiCHzU C O O R Compound 1 Compound 2 Compound 3 lira L Y CoHs @omom-N HA C O O R Compound 4 piperidine compounds and with processes for prepar- 30 wherein X is halogen, R is a methyl or ethyl radical, and ing these piperidine derivatives. More particularly, it HA1s an acld.

relates to N-(B-phenyethyl)-4-phenyl-4-carboalkoxypiperi- The reactions indicated hereinabove are conducted as dine compounds, and salts thereof, new compounds which '1 follows: 4r-phenyl-4-carbo(methoxy or ethoxy)-piperidine possess superior analgesic activity, and to the processof carbonate (Compound 2 hereinabove) is reacted with a preparing these new analgesic substances starting with .4- 13-phenylethyl halide (Compound 1) thereby forming N- phenyl-4-carboalkoxypiperidine. (fi-p y y p y y r y) The -N-(/3-phenylethyl)-4-phenyl-4-carboalkoxypiperipiperidine (Compound 3); the latter compound is re dines, and their salts, subject of the present invention may I acted with an acid to produce the corresponding salt of be-chernically represented by the following structural h -(fi-p l y 1 3 Y of f l V ethoxy) -piperidine (Compound 4). If desired, other acid addition salts of 4-phenyl-4-carbo-(methoxy or ethoxy)- 1. I 96116 piperidine may be used as well as the carbonate in pre Q O paring CompoundB;

. p 7 The reaction between the 4-phenyl-4-carbo(methoxy or wherein R is a methyl or ethyl radical; and HA is an ethoxy)pipen'dine carbonate and the ,B-phenylethyl halide acid 7 v a is conveniently conducted by heating the reactants tochemical e a o of 1 gether in a liquid medium which is substantially inert phenyl 4 carbomethoxypiperidine and N,([3 pheny1ethy1) under the reaction conditions and wh1ch 1s a solvent for 4 Pheny1 4 carboethoxy piperidinea to the we11 known the reactants. We ordinarily utilize, as the liquid med1um, analgesic, meperidine, is clear from a comparison of the a 1 a such as etha-HOL and Prefer f f foregoing formula with the structural formula of meperithe r by heatmg the leactams together In sald dine which is asfollows: alkanol solvent under reflux 1n the presence of a base '1 for example an alkali metal bicarbonate such as sodium 06m bicarbonate. *As the fi-phenylethyl halide starting magma-O terial, we can utilize the chloride, bromide or iodide, but

I ,-1 0 we ordinarily prefer to employ either fi-phenylethyl chloride or 'B-phenylethyl bromide. Utilizing these preferred Although meperidine has been widely us as an 3. reactants and under the preferred reaction conditions, the gesic, its toxicity has been a disadvantage in y reaction is ordinarily substantially complete in about stances. A large number of N-substituted analogues of one to two days. 1 The -(fl-p ll y -P Y meperidine have been prepared heretofore in the hope of carbo(methoxy or ethoxy)piperidine thus formed is conta g a mp n having comparable analgesic acveniently recovered from the reaction mixture by removtivity to meperidine an r d tOXiCitY, ut none of thc ing the inorganic salts by filtration, and evaporating the compounds thus prepared have offered a satisfactory resulting alcoholic solutionto dryness in vacuo. The substitute for meperidine; There was no reason to expect residual material is triturated with water, the water is from this prior work that this line of investigation would decanted, and the washed material is dried in vacuo to lead to an improved analgesic of the meperidine type, give N-(fi-phenylethyl)-4-phenyl -4 -carbo(methoxy or since it was found that increasing the molecular size of ethoxy)piperidine base. The conversion of the N-(B- the N-substituent actually increases the toxicity and rephenylethyl)-4-phenyl-4-carbo(methoxy or ethoxy)piperiduces the analgesic activity (e.g. N-benzyl-4-phenyl-4 dine base-to'the-corresponding salts is ordinarily concarboethoxypiperidine is reported to possess only one-half ducted by reacting the N-(B-phenylethyl)-4-phenyl-4- the analgesic activity of meperidine). carbo(methoxy or ethoxy)piperidine base, under substan- Surprisingly enough, the new compounds, N-(fi-phenyltially anhydrous conditions with an acid as, for example,

hyd o chloride, hy r gen bromide, sul uric a id and the like. This salt-forming reaction is conveniently carried out in a medium comprising a lower alkanol, such as .ethanol, methanol, prQP%I1Q1,-.and=t;he.like.. diluting the alkanol reaction medium with ether, there :piecjpi- ,tates the Salt of the N-(.B-phenylethyl)s4-phenyl-4-carbo (methoxy or ethoxy) piperidine :such as N-(.13- .phenylethyl)-4 phenyla4-carbomethoxy pmefiidine hydrochloride, N-' fi-phenylethyl;)-4 phenyl 4-earbomethoxypi peridine :hydrobromide, N-(fi phenylethyl) 4 phenyl-4- carbomethoxypiperidine sulfate, ,N-(fl-phenylethyl9-4- .phenyl-4-carboethoxypiperidine hydrochloride, ;Nj(5- .phenylethyl)4-phenyl-4 carboethoxypiperidine hydro-bro.- mide, -(fi-p y t y i)- r nMM-s: boe exypiperidine sulfate, and the like. The salt thus formed :is {re covered from the alcoholic slurry by filtration or centrifugation.

The following examples illustrate methods of carrying out thepresent invention, but it is .to he understood that these examples are given f o.r purposes of illustration :and not of limitation.

Example 1 A mixtureof 7 1g. .of 4-phenyl-4-carboethoxypiperidipe carbonate, 4.44 g. ofp-phenylethyl bromide, 4.2 g. of sodium bicarbonate and 60 ml. of absolute ethanol is heated under reflux for a period of approximately 48 hours. The reaction mixture .is .filte'red thereby removing inorganic .salts, and the ethanol is evaporated from the filtered solution in vacuo. The residual material is slurried with ether, filtered to remove additional inorganic material and the insoluble material washed with .additional ether. The filtered ether solution and washings may be evaporated to .dryness to give .N-(fi-phenylethyl} 4-phenyl-4-carboethoxypiperidinebase. 7

Alternatively hydrogen .chloride ,gas is added to the 4 lion may be evaporated to .dryness .to give N-(Ji-phenylethyl) -4-phenyl-4-carbomethoxypiperidine base.

Alternatively hydrogen chloride gas is added to the combined ether extracts containing the N-(fi-phenylethyD- 4-phenyl-4-carbomethoxypiperidine base whereupon N- .tfi-p enylethy )+4=p y Awafiomdhemineddin t ,drochloride precipitates immediately, and {is recovered by filtration to give about 3.8 g. of crude hydrochloride. This mat rial is p fied by r c y ta l z i n romet auo ether -:to give about 3.3 g. of substantially {pure :N-.(,6- phenylethyl)-4-phenyl-4acarbomethoxypiperidine hydroh1Qr .de;LM.P; 21 2 C. Ic t r -zi'H25Q z'N3H C, 70.07; H, 7.2&;3N,:, 3J 89;:f0l111dl (3, 70.05; H, 7.32; N, 3.90.

In accordance with the -.forego ing procedure and iutiilizing, in place of the anhydrous hydrogen chloride there employed, other anhydrous acids such as sulfuric acid, phosphoric acid, citric acid, oxalic acid or hydrogen bromide, there are obtained respectively N-(fl-phenylethyl)44aphenyla4-carbomethoxypiperidine sulfate, N-(B- phenylethyl)-4-phenyl 4 carbomethoxypiperidine phosphate, N- (,B-phenylethyl) -4-phenyl-4-carbomethoxypiperidine citrate, N- (fi-phenylethyl)-4-phenyl-4-carbomethoxypiperdine oxalate, N-(fl-phenylethyl)-4-phenyl-4-carbomethoxypiperidine hydrobromide, and the like.

The new compounds obtained as described hereinabove have been named as substituted piperidines. Alternatively they may be considered as derivatives of isonipecotic acid. Thus N-(fl-phenylethyl)-4-phenyl-4carbomethoxypiperidine may also be named as methyl 1-phenylethyl-4- phenyl-isonipecotate, and N-IB-phenylethyl)-4-phenyl-4- carboethoxy-piperidine named as ethyl-'l phenylethyllphenyl-isonipecotate.

combined filtered other solution and .ether .washings, U

whereupon ,a crystalline precipitate rforms immediately; this crystalline precipitate .is recovered by filtration .and purified by recrystallization from ethanol-ethergto give approximately 4 g. of substantially pure .,8 (;phenylethyl)- 4:phenyl-4-carboethoxypiperidine hydrochloride; ;M;P. 190-192" o. Analcalcd. for C22H NO' 'HCILC, 70:66; H, 7.55; found: C, 70.46; ,H, 7.31. a

Instead of adding hydrogen chloride ,gas textile-oombined .ether solution and washings .containing the I l-(flphenylethyl)4 pheny1-4-carboethoxypiperidine base we can add sulfuric acid, phosphoric'acid, citricacid, ,oxalic acid, or hydrogen bromide to such ,ether solution t thereby precipitating the corresponding salt --whi ch is recovered ,by filtration and dried to give, respectively, N-(fi-phenylethyl )-4-phenyl-4-carboethoxypiperidine sulfate, N tephenylethyl) -4-phenyl-4-carboethoxypip eridine phosphate, N ,B-phenylethyl)-4-pheny1-4carboethoxypiperidine citrate, N-( fi-phenylethyl) -4-phenyl.- 4 carboethoxypiperb dine oxalate, or N-(pZ-phenylethyl) -4;phenyl-4- earboethoxypiperidine hydrobromide.

Example 2 A mixture of 36 got 4-phenyl-4 carbomethoxypiperidine carbonate, 2.8 g. :of phenylethyl bromide, 2.3 ;g. of sodium bicarbonate, and 35 cc. .of absolute ethanol, is heated under reflux, with stirring, for a period .of approximately 40 hours. The reaction ;mixture is :filtered thereby removing inorganic salts whichare washed with three 15 cc. portions of absolute ethanol. The.combi ned ethanolic filtrate and washings are evaporated ,in .vacuo to a crystalline mush which .is dissolved in-a mixture of 15 cc. of ether and 15 cc. of water. The layers are separated and the aqueous layer is extracted .with 15 -.,c c. of ether. The combined etherextracts are dried-Overallhydrous magnesium sulfate .and thedriedethereal 591L1- Various changes and modifications may 'be made in carrying out the present invention without departing from the spirit and scope thereof. Insofar as these changes and modifications are within the purview of the annexed claims, they are to be considered as part of our inventron.

We claim:

1. N-( fi-phenylethyl)-4-phenyl=4 oarboethoxypiperidine.

2. N fi-phenylethyl)-4phenyl-4-carboethoxypiperidine hydrochloride.

3. N-(fi-phenylethyl)-4-phenyl-;4=carboethoxypiperidine phosphate.

4. N (p-phenylethyl)-4-phenyl-4-carbomethoxypiperidine hydrochloride. l I

5. A compound selected from the group consistingof compounds of the'formu'la:

OTHER REFERENCES Gilman et,al.: :J.An 1 er'. .Chen'1..Soc., ;vol. 47,-.pp. 25k 252 (192-5).

.Simons: Ind.;and Eng.. Gl1em.,-..vol. 39, ;p. 238 (1-1947z) 

1. COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF THE FORMULA: 